This application claims the benefit of German Patent Application DE 10139074.2, filed Aug. 9, 2001, herein incorporated by reference.
The present invention relates to an open-end rotor spinning machine, in particular to an open-end rotor spinning machine having at least two identical work stations wherein each work station has a stationary yarn guide device and a yarn catch element being cooperatively arranged.
As illustrated in German Patent Publication DE 198 36 065 A1, an open-end spinning machine typically has a plurality of identical work stations arranged in series next to each other. Each work station has an open-end spinning device and a winding device. At each work station, a sliver fed from a spinning can, for example, is spun into a yarn by means of the open-end spinning device and is subsequently wound into a cheese with the aid of the winding device.
The work stations are attended by a service unit that can be moved along the work stations. The service unit automatically intervenes when an interruption such as a yarn break occurs at one of the work stations. In such a case, the service unit moves to the affected work station and positions itself thereat. With a pivotably seated suction nozzle, the service unit searches for the ruptured yarn that has run up on the cheese.
In some situations, the individual work stations may have to wait too long for the service unit. This is the case when, for example, the service unit is still occupied with the elimination of an interruption at another work station. To avoid this delay, it has been proposed to employ several of the service units simultaneously at an open-end spinning machine.
However, service units such as those disclosed in German Patent Publication DE 198 36 065 A1 are all relatively complicated in their construction and, therefore, comparatively expensive.
In addition to the suction nozzle to which a vacuum can be applied, the service unit also has a number of yarn manipulating elements that make it possible for the service unit to search for the yarn that has run up on the cheese after a yarn break and to piece the picked-up yarn to a fiber ring rotating in the open-end spinning device.
A comparable driveable service unit is disclosed in German Patent Publication DE 25 41 589 A1 and is also designed for automatic piecing in the spinning devices of an open-end rotor spinning machine. The service unit of German Patent Publication DE 25 41 589 A1 also has a pivotably seated suction nozzle. The suction nozzle is slit over its entire length and in the area of its pivot axis makes a transition into a slit transfer arm. Moreover, a yarn storage device, as well as a yarn gripper, are installed in the area of the pivot axis of the suction nozzle and the transfer arm. The yarn that has run up on the cheese after a yarn break is pneumatically picked up by the suction nozzle, is inserted into the yarn storage device and is transferred to a yarn clamping and preparation device arranged at the end of the transfer arm.
Thereafter, the prepared yarn is displaced into the area of the spinning device by the pivoting of the transfer arm and is fed back into the spinning device through a small yarn withdrawal tube.
In addition, it is mentioned in German Patent Publication DE 25 41 589 A1 that, although the yarn processing devices of the service unit can be theoretically arranged in a stationary manner at every one of the work stations of the spinning machine, it is considerably more efficient to arrange these relatively elaborate and, therefore, expensive yarn processing devices on a driveable service unit. The driveable service unit then services a multitude of work stations of an open-end spinning device.
It is accordingly an object of the present invention to create an open-end spinning machine with independent work stations that are relatively simple in their structure.
This object is addressed by an open-end rotor spinning machine having at least two identical work stations, wherein each work station comprises an open-end spinning device for producing a yarn, a winding device with a creel, a yarn cross-winding device for producing a cheese, a vacuum-chargeable, pivotably seated suction nozzle having a yarn catch element arranged thereon, a device for preparing a yarn for piecing, and a stationary yarn guide device wherein the stationary yarn guide device and the yarn catch element are cooperatively arranged for retrieving the yarn from the cheese and transferring the yarn to the open-end spinning device.
The work stations of the open-end rotor spinning machine having a stationary yarn guide device and a yarn catcher element being cooperatively arranged makes it possible to simply pick up a yarn that has run up on the cheese and transfer it into the spinning device.
For example, a suction nozzle that is driven by a step motor as the single motor device and that is a part of the work station can pick up a yarn from the surface of a cheese maintained in the creel of a winding device and dependably transfer the picked-up yarn to a spinning member that is arranged in the open-end spinning device of the respective work station without requiring further manipulating devices.
Therefore, the independent work stations as a whole remain relatively simple in construction and are cost-effective.
Moreover, in the present invention, the design of the work stations allows the immediate and rapid repair of possibly occurring yarn breaks at any time so that the downtime of the work stations caused by yarn breaks can be minimized and, as a result, yarn breaks have a lesser impact on the efficiency of the work stations.
For this reason, it is also possible to efficiently produce less spin-resistant yarn in the work stations in accordance with the present invention.
In accordance with the present invention, it is possible to produce a yarn that has a clearly reduced coefficient of twist as compared to yarn produced by known work stations. Although it is therefore more likely to have possible yarn breaks, the result is a clear increase in the produced yarn length with the same number of rotor revolutions of the spinning device.
The work stations designed in accordance with the present invention result in a considerable increase in productivity of the work stations.
In one embodiment of the present invention, a stationary yarn guide device has a catch border arranged outside of the regular yarn travel path of the work station and has a catch border such that the yarn picked up by the suction nozzle slides when the suction nozzle is pivoted down. In this case, the catch border is arranged in such a way that in the course of the subsequent pivoting-up of the suction nozzle, the yarn remains fixed in place in this catch border and can be taken over by a corresponding yarn catch element arranged on the back of the suction nozzle.
Due to the cooperative arrangement between the stationary yarn guide device and the pivotably seated yarn catch element, it is possible to simply increase the yarn transfer path of the picked-up yarn past the pivot range of the suction nozzle.
In another embodiment, the suction nozzle is connected with the vacuum source by means of a valve that can be controlled by a work station computer. The suction nozzle is thus only charged with a vacuum when needed. This is due to the employment of the valve. Unnecessary air consumption and useless energy consumption are avoided.
In another embodiment of the present invention, the yarn catch element arranged at the back of the suction nozzle is formed from steel sheet metal. In yet another embodiment of the present invention, the yarn catch element has at least one yarn guide edge and a yarn catch border. The yarn catch element may also have a shift plate.
The yarn guide edge may be curved in an S-shape. This assures that in the course of upward pivoting of the suction nozzle, the yarn that is held in readiness in the yarn catch border of the stationary yarn guide device dependably reaches the yarn catch border of the pivotably seated yarn catch element. Preferably, the yarn catch border is V-shaped. The V-shaped yarn catch border assures that during the subsequent pivoting-away of the suction nozzle the yarn is correctly taken along and is transferred to a yarn processing and return device arranged in the open-end spinning device.
In the yarn transfer position of the suction nozzle, the shift plate of the yarn catch element cooperates with an area of a piecing member arranged in the open-end spinning device.
The shift plate that runs up against a corresponding detent of the piecing member pivots the piecing member out of its spinning position into a yarn receiving position such that the yarn can be pneumatically picked up by the piecing member.
It is moreover possible for a yarn centering device, preferably designed as a centering plate, to be arranged in the winding device. For example, this yarn centering device together with a yarn guide edge in the aspirating opening of the suction nozzle assures that the picked-up yarn always travels in a defined position during its conveyance to the piecing member.
It is assured in this way that the yarn correctly slides into the catch border of the stationary yarn guide device and that it is also dependably taken over by the catch border of the pivotably seated yarn catch element.
Further details of the invention can be gathered from a non-limiting exemplary embodiment presented in the following description with reference made to the drawings.